Liquid nonaqueous detergents are well known in the art. This class of detergents is particularly interesting for enhancing the chemical compatibility of detergent composition components, in particular bleaching agents.
In such nonaqueous products, at least some of the normally solid detergent composition components tend to be less reactive with each other than if they had been dissolved in the aqueous liquid matrix.
Even though chemical compatibility of components may be enhanced in nonaqueous liquid detergent compositions, physical stability of such compositions may become a problem. This is because there is a tendency for such products to phase separate as dispersed insoluble solid particulate material drops from suspension and settles at the bottom of the container holding the liquid detergent product. As one consequence of this type of problem, there can also be difficulties associated with incorporating enough of the right types and amounts of surfactants, in particular anionic surfactants, into nonaqueous liquid detergent products. Anionic surfactants must, of course, be selected such that they are suitable for imparting acceptable fabric cleaning performance to such compositions but utilization of such materials must not lead to an unacceptable degree of viscosity increase. Viscosity control agents can be added to such products to improve the physical stability thereof. Such materials, however, can add cost and bulk to the product without contributing to the laundering/cleaning performance of such detergent compositions.
Given the foregoing, there is clearly a continuing need to identify and provide liquid, anionic-containing detergent compositions in the form of nonaqueous liquid products that have a high degree of physical stability along with commercially acceptable pourability. Accordingly, it is an object of the present invention to provide nonaqueous, anionic-containing liquid detergent products which have such especially desirable physical stability characteristics as well as outstanding pourability characteristics.
Nonaqueous liquid detergent compositions containing high level of anionic surfactants are described in DE 3 728 047, EP 484 095 and WO 92/09678. None of the art teaches, discloses or suggests that selectivity of the alkylbenzene sulfonates results in a liquid nonaqueous detergent composition with excellent physical and pourability characteristics.
Matheson and Matson, J. Am. Oil. Chem. Soc. 60:9 (1983) reported on the effect of carbon chain and phenyl isomer distribution on use properties of linear alkylbenzene sulfonate, a comparison of "high" and "low" 2-phenyl LAS homologs. The 2-phenyl content varies with the type of alkylation catalyst, as HF produces 19% 2-phenyl and AlCl.sub.3 produces 29% 2-phenyl. The authors reported that the 2-phenyl content had little effect on LAS performance in both light-duty and heavy-duty detergent applications, and the carbon-number chain size is far more important.